Open RAN in a suburb. A suburb served by one Open RAN site. Every function sits where it runs, and every interface is drawn.

Layers

Scenario

A suburb served by one Open RAN site. Every function sits where it runs, and every interface is drawn.

01/08

n78 3.5 GHz: 3.30–3.80 GHz · λ 84.4 mm · Main 5G capacity layer, massive MIMO · 3GPP TS 38.101-1

Network scenes

Open RAN in a suburb

A disaggregated site: the radio unit on the mast, the distributed unit in the cabinet, the central unit and near-real-time RIC at the edge, the non-real-time RIC and SMO in the cloud, with every interface drawn and named.

The place: Suburb

In this scene

O-RU, radio unit

The radio and antenna array at the top of the mast: the low physical layer (beamforming, FFT) under split 7.2x, everything above it moves off the mast. (O-RAN.WG4.CUS.0, O-RAN.WG4.MP.0, 3GPP TS 38.104)
Split: 7.2x: low PHY in the O-RU · Scene input: 72 dBm EIRP per sector, 6° downtilt

O-DU in the street cabinet

High PHY, MAC and RLC for the three sectors, in the cabinet at the foot of the mast; it is timed from a PTP grandmaster. (O-RAN.WG4.CUS.0, ITU-T G.8275.1, 3GPP TS 38.401)

O-CU-CP and O-CU-UP at the edge

PDCP and RRC for many sites, on the edge cloud a few kilometres away. (3GPP TS 38.401, 3GPP TS 38.470 (F1), 3GPP TS 38.460 (E1))

Near-RT RIC with xApps

Control loops of 10 ms to 1 s: xApps read RAN measurements over E2 and act on scheduling, beams and handover. (O-RAN.WG3.E2AP, O-RAN.WG3.E2SM-KPM, O-RAN.WG3.E2SM-RC)

SMO and Non-RT RIC with rApps

Service management and orchestration in the regional cloud; the non-real-time RIC (loops over 1 s) runs rApps and sets policy for the near-RT RIC. (O-RAN.WG1.OAD, O-RAN.WG2.A1AP, O-RAN.WG2.R1GAP, O-RAN.WG10.O1-Interface.0, O-RAN.WG6.O2-GA&P)

5G core

The core network functions the central unit attaches to over NG. (3GPP TS 23.501, 3GPP TS 38.410 (NG))

Links and interfaces

Open Fronthaul 7.2x

Fibre down the mast to the cabinet: control, user and synchronisation planes over eCPRI on Ethernet, plus the management plane. (O-RAN.WG4.CUS.0, eCPRI 2.0, eCPRI Transport Network V1.2)

Midhaul (F1)

The F1 interface between distributed and central units, carried on the operator’s midhaul fibre. (3GPP TS 38.470)

E2

Measurements up and control down between the near-RT RIC and the E2 nodes (O-DU, O-CU). (O-RAN.WG3.E2AP)

A1

Policies and enrichment information from the non-RT RIC to the near-RT RIC. (O-RAN.WG2.A1AP)

O1

Configuration, performance and fault management of every O-RAN managed element. (O-RAN.WG10.O1-Interface.0)

O2

Management of the O-Cloud: the edge servers the CU and the RIC run on. (O-RAN.WG6.O2-GA&P)

NG to the core

The central unit attaches to the 5G core in the regional cloud, about 40 km away. (3GPP TS 38.410)

Computed for this scenario

Outdoor area at SINR ≥ 10 dB

77 %

Median SINR

20.3 dB

Shannon bound at median, 100 MHz

677 Mbit/s

Cell edge (5th percentile)

2.3 dB · 142 Mbit/s

SSB beams per burst (TS 38.213)

8

User beams steered

1

Array gain, 64 elements

18.1 dB

Beamwidth, azimuth

12.8°

Open Fronthaul 7.2x

51 m · 0.3 µs of 100 µs (within)

Midhaul (F1)

726 m · 3.6 µs one way

NG to the core

40.0 km · 196 µs one way

Scenarios

Normal

Three sectors on air; the RIC loops run.

Sector B fails

Sector B drops. The outage shows in the coverage and in the E2 measurements.

RIC compensates

An rApp sets a coverage policy over A1; the xApp uptilts sectors A and C by 4° and widens their reach.

Fronthaul 25 km

The distributed unit moves to a hub 25 km away: the fronthaul delay passes the 100 µs class.

Tour transcript

1. A suburb served by one Open RAN site. Every function sits where it runs, and every interface is drawn.
2. The O-RU on the mast does the low physical layer; the fibre down the mast is the Open Fronthaul.
3. The O-DU in the cabinet at the foot of the mast, timed by PTP.
4. At the edge: the central unit and the near-real-time RIC with its xApps, joined by E2.
5. In the regional cloud: SMO, the non-real-time RIC and its rApps, and the core. A1, O1 and O2 run from here.
6. Sector B fails: the hole shows in the coverage and in the E2 measurements.
7. An rApp policy over A1, an xApp action over E2: sectors A and C uptilt and recover part of the area.
8. Move the distributed unit 25 km away and the fronthaul passes its 100 µs delay class.

How the numbers are computed

Coverage uses 3GPP TR 38.901 UMa path loss with line of sight against the terrain and buildings and the TR 38.901 sector pattern. Fibre delay is the routed length times 4.9 µs per km (group index 1.468). The 100 µs fronthaul class is the eCPRI Transport Network High100 class. RIC loop times are the O-RAN architecture classes (near-RT 10 ms to 1 s; non-RT over 1 s).